Design of single chip microcomputer control system for automatic chamfering machine of magnetic tile

Introduction
With the rapid development of China's manufacturing industry, production automation has also developed rapidly. The electromechanical control system based on single-chip microcomputer is an important field of production automation. It has high control precision, powerful functions, accuracy and reliability. The production of magnetic tile chamfering is a large-scale industrial production object. The manual production efficiency is low and the finished product is not high. Using single-chip microcomputer to control the servo motor to realize each process to complete the production of magnetic tile chamfering can greatly improve labor productivity and production automation.

System principle of chamfering machine
The control system requires the motor to drive the main pulley of the chamfering machine to make intermittent movements. When the pulley moves, the chamfering machine completes unloading and grinding the left and right end faces. When the pulley stops, the left outer arc, right outer arc, left inner arc, right inner arc, outer chamfer and inner chamfer of the workpiece are completed at the corresponding stations. The magnetic tile part is shown in Figure 1. The system working principle of the automatic chamfering machine is shown in Figure 2.
First, the motor drives the conveyor belt to move, so that the magnetic tile part passes through the first pair of grinding wheels to complete the grinding of its left and right end faces. When it moves to the left outer arc grinding station, it stops moving, and the corresponding cylinder pushes it from the conveyor belt to the grinding wheel grinding position, and keeps it for at least 0.2 S to complete the grinding of the grinding wheel. After grinding, the cylinder and the corresponding mechanical mechanism return the magnetic tile to the conveyor belt and start moving to the next station. Until all stations are ground, the material is unloaded. The process flow is shown in Figure 3.

According to the above process flow chart, after comprehensive consideration, the working sequence of the magnetic tile chamfering machine is designed. The transmission belt motor performs intermittent motion, moving for 0.6 s and stopping for 0.9 s. During the stopping time, the six cylinders complete the processing on each station respectively. The hardware design of the control system is based on the designed sequence and the functions to be completed. The single-chip microcomputer STC8051 is selected as the core to form the motion controller to control the Yaskawa servo motor to perform intermittent motion. The block diagram of its computer control system is shown in Figure 4. The upper industrial computer: write and send instructions, and send the instructions to the motion controller. After the motion controller translates, it is sent to the servo amplifier to drive the servo motor to achieve the required motion. Motion controller: This motion controller is composed of the core. Users can use its instruction set to write the corresponding program on the upper computer, and after the motion controller translates, it is sent to the servo amplifier. Servo amplifier: controls and drives the servo motor to perform the corresponding motion by receiving external signals. Servo motor: the actuator of the action, drives the belt to perform the required intermittent motion.
The system selects STC8051 as the microcontroller, which has 8K Flash ROM inside, and can realize in-system programming. The internal Flash memory of the microcontroller is programmed through the programming line, clock line, reset line, etc. output by the single-chip microcomputer. The programming line is shared with the P1 port line, and there is no need to add extra pins of the single-chip microcomputer. This circuit selects whether the single-chip microcomputer is in operation mode or programming mode through a micro-switch. When the system is in programming mode, there is no need to remove the controller chip. The host computer software is used to program and debug the internal Flash memory of the single-chip microcomputer through the download cable and interface, which is convenient for on-site operation and maintenance. In the working position control mode of the servo motor, the command pulse and command symbol are input to the servo amplifier through the P21 output terminal of the single-chip microcomputer, so as to control the motor to rotate only at an angle proportional to the input pulse. P22 uses the /CLR input to the servo amplifier to complete the zeroing of the position offset. X1, connected to the crystal oscillator to generate input pulse signal. [page]

The pulse signal required by the servo is generated by the single-chip microcomputer timer T0 interrupt. When T0 is operated in the square 2 timing mode, the theoretical timing length is (28 count initial value) · 1s when the oscillation frequency is 12 MHz. However, when the interrupt is generated, a certain instruction may be running, and some other work will be done after entering the interrupt. Therefore, the output frequency calculated by the timing length is slightly different from the actual output. If the initial count value is 0 FOH, an interrupt can be generated after 16 instruction cycles. In the interrupt program, the PULSE (pulse pin) is reversed. In this way, theoretically, a pulse signal can be output in about 40 instruction cycles. The frequency is 25 kHz. When the initial count value increases, some interrupts cannot be responded to because the microcontroller processing takes a certain amount of time. In fact, the output pulse signal frequency will not increase. The actual measurement found that in a 12 MHz crystal N, the pulse output of N~TNN is about 20 kHz, and the servo motor needs 2048 pulse signals to rotate one circle, so the maximum speed is about 600 r/min: it meets the speed required for the motor to work. The system program flow chart is shown in Figure 5.
First, the command pulse, direction signal, input clear signal, MAIN function entry and timer interrupt entry are initialized. Then execute the MAIN function, input the control signal to make the motor rotate forward for 10.5 circles, then stop and wait for 0.6 s, and then detect whether there is an alarm. If not, execute the MAI N function repeatedly; if yes, stop the motor, turn off the power, eliminate the alarm, turn on the power again, and run.

Conclusion
This paper analyzes the system principle of the magnetic tile chamfering machine, selects the single-chip microcomputer STC 8051 to form the Hefu Electric Motor motion controller, and then achieves the desired function through programming. The control system has been successfully applied in the project. It is believed that it will promote the automated production of magnetic tile chamfering machines. The control system can also be extended to the production of other similar products.